Abstract

This study established the relationship among different soil properties such Al-, Fe-complexes and allophane content on soil C levels in Chilean volcanic soils as well as the effect of soil pH on metal–OM complexes. A total of 45 soil samples from 15 soil pedons were sampled. The soil samples were analysed for the content of soil organic C, allophane, clay, silt and Na- pyrophosphate extraction (Alp, Fep, Cp) and soil pH (water). The AA. examined the relationship between the soil C content and soil properties using simple and multiple linear regressions. The silt and clay contents explained little, while the allophane, soil pH and Alp explained most of the soil C variation. In contrast to the top soil, SOM in the subsoil was saturated with Alp and Fep. Soil pH and metal : soil C ratio regulates SOM–allophane association in the soil profile